Effective Photon Mass in Finite Nuclei
- Received Date: 2002-07-12
- Accepted Date: 1900-01-01
- Available Online: 2003-04-05
Abstract: The electromagnetic field in nuclear Fermi gas and nuclei has been studied. Because in the nuclear Fermi gas the expectation value of the electric charge density operator is not zero, different from that in vacuum, the U(1) local gauge symmetry of electric charge is spontaneously broken in the nuclear Fermi gas, and consequently, the photon gains an effective mass. Perturbation calculation of the photon self-energy shows that the effective mass of photon is about 5 42MeV in the symmetric nuclear Fermi gas at the saturation density ρ0=0.16fm－3 and about 2.0MeV at the surface of 238U. Furthermore, it is concluded that it is just the two body decay of a massive photon that causes the discovery of sharp lines of electron positron pairs in low energy 238U+232Th heavy ion collisions experiments.